Various bus systems are known for transmitting messages between user stations or communications nodes of a communications system, for example between control units in a communications network of a vehicle. In so-called CAN bus systems, messages are transmitted using the CAN protocol described in the CAN specification in ISO 11898. Further examples of such bus systems are FlexRay, LIN, MOST and Ethernet. In many cases, the standardization is operated by a contractual alliance (consortium, association). An overview of currently used bus systems may be obtained, for example, from the following book by Werner Zimmermann and Ralf Schmidgall: “Bussysteme in der Fahrzeugtechnik—Protokolle, Standards and Softwarearchitektur” (“Bus systems in automotive technology—protocols, standards and software architecture”), Vieweg+Teubner, 4th edition, 2010.
A communications system is also known in which messages are transmitted with the aid of the Ethernet standard, which is defined by the IEEE 802 standards family.
AUTOSAR (AUTomotive Open System ARchitecture) refers to a development association of various companies in the automotive industry pursuing the objective of simplifying and harmonizing data communication and software exchange between control units of a vehicle. The relevant descriptions and the terminology used by Autosar may be found, for example, in the publicly available Autosar Specifications 3.2 and 4.0.
The growing volume of data in modern vehicles and the increasing networking of the vehicle both internally and outwardly make new communications technologies and architectures necessary in the vehicle in order to meet the requirements regarding safety, comfort and data rate and, at the same time, keep the complexity of the vehicle network manageable. The coupling of a plurality of communications networks of a communications system, also called sub-networks of the communications system, by a gateway is a customary approach to managing data volume. With that approach, communications nodes that communicate extensively with one another are usually placed in a common network and the gateways make specific, selected messages available in the various networks. A large proportion of the data is forwarded by a gateway usually transparently without being manipulated.
International Patent Application WO 2009/156820 A1 describes a method for establishing communication between communications nodes, in which a plurality of wireless communications networks are connected by suitable gateways to a connection network, called a backbone, and wired communication takes place between the gateways via the backbone. In that manner, the communications nodes of various communications networks are able to communicate with one another. In this case, the gateways have the task of forwarding messages or their useful data, and various possibilities for doing this are presented.
German Patent Application DE 10 2006 055 513 A1 discusses a multiprocessor gateway by which a plurality of communications networks may be connected to one another, in which a computer unit or gateway unit provided for that purpose ensures the communication between the connected communications controllers by using a system bus kept especially for the purpose.
It is problematic, however, that the discussed gateway technologies may have inadequate latency times owing to their use of known computer architectures. On the other hand, an architecture with sub-networks (meaning communications networks whose users communicate with one another via a continuous medium and using a common communications protocol) and a backbone (connection network) is only able to display its advantages properly if the communication of the sub-networks may be extended flexibly and transparently by way of the backbone while retaining quality of service (QoS) and without placing too great a load on processors.